Plate heat exchanger

Abstract

The invention relates to a plate heat exchanger (1) of the type comprising an impervious chamber (2), a bundle of plates (3) arranged in said chamber (2) and providing therewith a free space (4), an inlet pipe (10) for hot fluid in a first circuit of this bundle (3), an outlet pipe (12) for the cooled fluid, an inlet pipe (20) for a cold fluid communicating with the inlet of the second circuit of this bundle (3), and an outlet pipe (21) for the heated fluid. The heat exchanger also comprises means (25) for channelling the cold fluid along the internal wall of the chamber (2).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plate heat exchanger.

2. Description of the Related Art

Plate heat exchangers are generally formed by an elongate impervious chamber and by a bundle of plates arranged in said impervious chamber and providing therewith a free space. The bundle of plates consists of a stack of mutually parallel plates that provide between them a double circuit for the flow of two independent and generally counter-current fluids.

This type of heat exchanger also comprises an inlet pipe for a hot fluid that is connected by a connection box, also known as a collector, directly to the input of the first circuit of the bundle of plates, which flows into one of the circuits of this bundle, and an outlet pipe for the cooled fluid once it has passed into said bundle of plates, which outlet pipe is connected by a connection box directly to the outlet of this first circuit.

In order to cool this hot fluid, heat exchangers of this type also comprise an inlet pipe for a cold fluid flowing into the other of the circuits of the bundle of plates, which inlet pipe is connected directly by a connection box to the inlet of the second circuit of this bundle of plates, and an outlet pipe for this heated fluid once it has passed into said bundle of plates. This outlet pipe for the heated fluid is also connected directly by a connection box to the outlet of the second circuit of the bundle of plates.

The flow of the two fluids into the bundle of plates thus causes a heat exchange between these fluids.

The heat exchange between the hot and cold fluids along the bundle of plates subjects the wall of the chamber to temperature variations over its length. In the inlet region for the hot fluid, the wall of the chamber is subjected to an elevated temperature, while the temperature decreases gradually along this wall as a function of the cooling of the hot fluid in the bundle of plates.

The chamber is generally formed by a plurality of shells placed end to end and joined together, in particular by welding. In view of the variations in temperature, each shell has in the past had a different thickness, determined as a function of the temperature to which it is subjected.

These differences in thickness therefore mean that manufacturers have to provide various shells for a single exchanger, and this of course increases costs and makes the joining together of these shells more complex.

The object of the invention is to propose a plate heat exchanger that avoids these drawbacks and that provides a chamber of uniform thickness over its entire length.

SUMMARY OF THE INVENTION

The invention therefore relates to a plate heat exchanger of the type comprising:

• • an elongate impervious chamber;
  • a bundle of plates arranged in said impervious chamber and providing therewith a free space, said bundle consisting of a stack of mutually parallel plates that determine between them a double circuit for the counter-current flow of two independent fluids;
  • an inlet pipe for a hot fluid, connected directly to the inlet of the first circuit of the bundle;
  • an outlet pipe for the cooled fluid, connected directly to the outlet of said first circuit;
  • an inlet pipe for a cold fluid communicating with the inlet of the second circuit of the bundle that is remote from the inlet of the first circuit; and
  • an outlet pipe for the heated fluid, connected directly to the outlet of said second circuit that is remote from the outlet of the first circuit;
    characterised in that it comprises means for channelling the cold fluid along the internal wall of the chamber, between the inlet pipe for this cold fluid and the inlet of the second circuit of the bundle.

According to other characteristics of the invention:

• • the means for channelling the cold fluid comprise an internal case comprising a first wall arranged above the inlet of the first circuit and the outlet of the second circuit, and a second wall arranged in the free space and providing with the internal wall of the chamber an annular passage for said cold fluid;
  • the second wall of the internal case extends over a portion of the length of the bundle of plates;
  • the first wall of the internal case is planar or hemispherical or conical; and
  • the inlet pipe for the hot fluid, the inlet pipe for the cold fluid and the outlet pipe for the heated fluid are arranged in the region of the same end of the chamber.

The characteristics and advantages of the invention will become apparent from the following description, which is given by way of example and with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic longitudinal section of a plate heat exchanger according to the invention; and

FIG. 2 is a cross-section taken along the line 2-2 in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a plate heat exchanger, which is designated in its entirety by the reference numeral 1 and which comprises, on the one hand, an elongate impervious chamber 2, which is arranged, for example, vertically, and, on the other hand, a bundle of plates 3 placed in said chamber 2 and providing therewith, around said bundle, a free space 4.

The bundle of plates 3, which is generally parallel-piped in shape, consists of a stack of mutually parallel plates (not shown) that provide between them a double circuit A and B for the flow of two independent and, for example, counter-current fluids.

The heat exchanger 1 also comprises an inlet pipe 10 for a hot fluid that is connected directly by a connection box 11, also known as a collector, to the inlet A1 of the first circuit A of the bundle of plates 3, and an outlet pipe 12 for the cooled fluid once it has passed into the bundle of plates 3, which outlet pipe is connected directly by a connection box 13 to the outlet A2 of said first circuit A. In the embodiment illustrated in the figures, the hot fluid thus flows downwardly into the bundle of plates 3.

The heat exchanger 1 also comprises an inlet pipe 20 for a cold fluid that communicates with the inlet B1 of the second circuit of the bundle of plates via the free space 4 provided between the bundle of plates 3 and the chamber 2.

The inlet B1 of the second circuit B is remote from the inlet A1 of the first circuit A of the bundle of plates 3.

Finally, the heat exchanger 1 also comprises an outlet pipe 21 for the heated fluid once it has passed into the second circuit B of the bundle of plates 3, which outlet pipe is connected to the outlet B2 of this second circuit B by a connection box 22. The cold fluid therefore flows upwardly from the bundle of plates 3.

As shown in FIG. 1, the inlet pipe 10 for the hot fluid, the inlet pipe 20 for the cold fluid and the outlet pipe 21 for the heated fluid are arranged in the region of the same end of the chamber 2 and, in the embodiment illustrated in this figure, at the upper end of this chamber 2.

The plate heat exchanger 1 comprises means 25 for channelling the cold fluid along the internal wall of the chamber 2, between the inlet pipe 20 for this cold fluid and the inlet B1 of the second circuit B of the bundle of plates 3. As shown in FIG. 1, these means for channelling the cold fluid comprise an internal case 25, which comprises a first wall 26 arranged above the inlet A1 of the circuit A and the outlet B2 of the circuit B, and a second wall 27 arranged in the free space 4 between the chamber 2 and the bundle of plates 3 and providing with the internal wall of this chamber 2 an annular passage 5 for the cold fluid.

In the embodiment illustrated in FIG. 1, the first wall 26 is planar. This wall 26 may have other shapes, for example a hemispherical or conical shape, in order to promote the flow of the cold fluid into the annular passage 5.

As a result of the positioning of the internal case 25 between the inlet pipe 20 for the cold fluid and the inlet B1 of the second circuit B of the bundle of plates 3, the cold fluid flows into the annular passage 5 along the internal wall of the chamber 2 and therefore cools this chamber 2. The wall 27 of the internal case 25 extends over a portion of the length of the bundle of plates 3 so as to direct the cold fluid flowing into the annular passage 5 toward the inlet B1 of the second circuit B of the bundle of plates 3, as illustrated by the arrows F in FIG. 1.

The internal case 25 is held, for example, by welding the wall 26 to the inlet pipe 10 and to the outlet pipe 21.

The flow of the cold fluid along the internal wall of the chamber 2 allows this chamber 2 to be cooled, and this has the advantage of allowing this chamber 2 to be produced with shells (not shown), placed end to end and each having the same thickness, thus allowing these shells to be joined together and reducing the cost of manufacturing and producing this chamber.

Claims

1. Plate heat exchanger of the type comprising:

an elongate impervious chamber;

a bundle of plates arranged in said impervious chamber and providing therewith a free space, said bundle consisting of a stack of mutually parallel plates that determine between them a double circuit for the counter-current flow of two independent fluids;

an inlet pipe for a hot fluid, connected directly to the inlet of the first circuit of the bundle of plates;

an outlet pipe for the cooled fluid, connected directly to the outlet of said first circuit;

an inlet pipe for a cold fluid communicating with the inlet of the second circuit of the bundle that is remote from the inlet of the first circuit;

an outlet pipe for the heated fluid, connected directly to the outlet of the second circuit of the bundle that is remote from the outlet of the first circuit of this bundle of plates;

wherein it comprises means for channelling the cold fluid along the internal wall of the chamber, between the inlet pipe for the cold fluid and the inlet of the second circuit of the bundle of plates.

2. Plate heat exchanger according to claim 1, wherein the means for channelling the cold fluid comprise an internal case comprising a first wall arranged above the inlet of the first circuit and the outlet of the second circuit, and a second wall arranged in the free space and providing with the internal wall of the chamber an annular passage for said cold fluid.

3. Plate heat exchanger according to claim 2, wherein the second wall of the internal case extends over a portion of the length of the bundle of plates.

4. Plate heat exchanger according to claim 2, wherein the first wall of the internal case is planar or hemispherical or conical.

5. Plate heat exchanger according to claim 3, wherein the first wall of the internal case is planar or hemispherical or conical.

6. Plate heat exchanger according to claim 1, wherein the inlet pipe for the hot fluid, the inlet pipe for the cold fluid and the outlet pipe for the heated fluid are arranged in the region of the same end of the chamber.

7. Plate heat exchanger according to claim 2, wherein the inlet pipe for the hot fluid, the inlet pipe for the cold fluid and the outlet pipe for the heated fluid are arranged in the region of the same end of the chamber.

8. Plate heat exchanger according to claim 3, wherein the inlet pipe for the hot fluid, the inlet pipe for the cold fluid and the outlet pipe for the heated fluid are arranged in the region of the same end of the chamber.

9. Plate heat exchanger according to claim 4, wherein the inlet pipe for the hot fluid, the inlet pipe for the cold fluid and the outlet pipe for the heated fluid are arranged in the region of the same end of the chamber.